1. Field of the Invention
The present invention relates to a weapon suppressor system capable of minimizing the gas backflow to the operator and to the weapon's operating system, as well as, minimizing the weapon flash—the system comprising a unique central baffle and bypass system.
2. Description of the Related Art
Firearm suppressors are designed to attach to the muzzle of a weapon and reduce the noise and flash generated by said weapon when it is fired. While there are numerous suppressor designs which may accomplish this, an issue which remains is how to accomplish this while not affecting the overall performance of the weapon, especially high rate of fire weapons such as machine guns and carbines. Typical baffle sections in most suppressors do not allow for rapid blowdown of the weapon due to supersonic flow choking effects at each baffle section. As a result the flow chokes and slows blowdown of the weapon at each section. As a result, pressure and temperature gradients form in the suppressor. This often cause slow blowdown, high pressure at the breech during weapon cycling, high pressure sections in the suppressor, which may require significant wall thickness and added weight, and higher temperatures in the high pressure sections.
Proper management of weapon blowdown is critical for several reasons. Weapon blowdown is the rate at which the weapon barrel empties the propellant gases after the projectile leaves the weapon. Suppressors, when added to a weapon typically reduce the blow down rate and increase the back pressure in the weapon. In addition they can cause an “organ pipe effect” whereby pressure waves to ring back and forth in the barrel/suppressor system.
A primary effect of the reduced blowdown is an increases in pressure at the breech during case ejection of automatic or semi-automatic weapons. Case extraction can occur within milliseconds of firing and breech pressures with a suppressor installed can be 2 to 3 orders of magnitude higher if blowdown is not properly managed. This high pressure can cause case ejection problems, propellant fouling, propellant gases in the operators face and other problems. In addition, a reduced blowdown rate can cause changes in weapon powering of either piston driven or gas tube driven weapons. The decreased blowdown rate causes the pressure at the barrel gas port to be higher for a longer period of time and hence provides more power to the gas piston or gas operating mechanism. This can cause increased bolt velocities beyond weapon design limits and potentially damage weapon parts unless pressures can be reduced at the gas port by some means.
In order to increase the blowdown rates of a weapon with a suppressor it is critical to provide good blast overpressure reduction while at the same time emptying the suppressor can as fast as possible. The critical issue with regards to blowdown management of weapon suppressors is to increase the blowdown rate while not increasing the blast overpressure levels significantly.
Low visual signature is often important as well, to reduce the ability of an enemy to visually locate a firing position. Weapon flash may be caused by unburnt propellant at high temperatures exiting the suppressor where it mixes with the outside air and ignites. Reducing this flash is desirable.
Thermal management of weapon suppressors is also critical because they tend to absorb large amounts of heat when placed on a weapon. Suppressors have much larger internal surface areas than weapon barrels and as a result can absorb more heat from the propellant gases. While some suppressors may reduce the pressure of the exiting flow by acting as a heat sink to absorb thermal energy, thereby cooling the gas and reducing its volume, this effect would rapidly diminish with each shot of an automatic weapon, where the suppressor would heat up and no longer be able to cool the gas to reduce pressure.
Thus there is a need for a suppressor which can rapidly blowdown the contained pressure when used with a rapid firing weapon, while providing good sound suppression and minimizing visual signature and effectively managing thermal energy. This is accomplished through a combination of various design features described below.
A comparison to prior art U.S. Pat. No. 8,286,750 B1—‘Energy Capture and Control Device’, hereafter referred to as '750, is made here.
'750 is an “energy capture and control” device. Because of the large surface area and extensive turning through the use of multiple tubes, multiple internal wall, a serpentine flow path as a method to lengthen the flow path, it is expected that this will produce a device that “dissipates energy transferred from the high energy material” to the suppressor structure. Hence the suppressor becomes a heat sink for the high temperature propellant gases. This is accomplished by both increasing the turbulence of the flow by providing multiple and aggressive turning as well as providing large surface area or large contact area with the gas to increase heat transfer to the suppressor. It has been shown that pulling heat from the gases reduces the pressure of the gases and reduces the blast overpressure. This shows that one of the primary ways this suppressor functions is through temperature reduction of the gases. The '750 design is well suited to low rate of fire weapons such as sniper rifles and potentially some carbines. Otherwise the suppressor will soon reach peak temperature and no longer provide sufficient sound reduction since the suppressor is too hot to capture energy and reduce sound. Hence it should be noted that the '750 sound suppression technique utilized is primarily temperature reduction of the gas which in turn provides a pressure reduction. It is not primarily a pressure reduction device.
The off axis flow in '750 uses a serpentine flow path. The multiple internal walls actually decrease the volume of the fluid expansion, not increase it. The volume of the wall material reduces the available expansion volume and hence reduces the pressure reduction of the suppressor which would be due to volume increase. While the internal walls of '750 do increase the flow path length by using a “radially serpentine” flow path which cases the flow to go back and forth in addition to going around the central chamber due to the helical internal wall structure, creating gas turning, increased turbulence, and high amounts of wall heat transfer, the high heat transfer rate to the wall of the prior art will only work as long as the suppressor heats up to an a reasonable operating temperature after a limited number of shots. As a result, the '750 design losses effectiveness as it heats up since it gets its suppression primarily through temperature reduction.
Further by adding four to five inner tubes to the inside of the suppressor, the additional internal surface area is significantly higher. Heat transfer is typically proportional to surface area until the gas cools sufficiently that heat transfer to the wall no longer happens. As a result, the prior art suppressor will have more total heat transferred to the suppressor per shot. In a machine gun situation, the heating rate will be higher and the final temperature after a given number of rounds should be higher.
The inner tube system also drastically reduces the effective cross-sectional area significantly. As a result, the effective cross-sectional area is likely less than the exit area of the suppressor. As a result, flow could choke at any given point along the very long flow path. This could increase blow down time. Short blowdown time is critical for machine gun suppressors. The choked flow would lead to increased back pressure and blowback in a rapid fire situation, which could blow back towards the operator and could stress and potentially damage or disrupt the operating system.
K-baffles are utilized in suppressors as discussed in the background of U.S. Pat. No. 7,987,944 ‘Firearm sound suppressor baffle’: One typical conventional baffle is referred to as a “K-baffle,” . . . . The K-baffle is generally defined by a rear plate portion that is generally flat and oriented transverse to the axial bore of the suppressor and a forward bell portion extending in a forward direction from the rear plate portion along the longitudinal axis of the K-baffle. The rear plate portion includes a central aperture for a projectile to pass through the K-baffle in the forward direction. The forward bell portion increases in annular cross-section from the central aperture and rear plate portion to a forward end, which is configured to about a rear plate portion of a subsequent K-baffle. Thus, the K-baffle defines an interior chamber within the forward bell portion and an exterior chamber between the rear plate portion and the forward bell portion outside of the forward bell portion. The interior chamber and exterior chamber is typically fluidly connected by a flow aperture cut into the forward bell portion. Consequently, a plurality of K-baffles defines a plurality of blast chambers for the burning gases to expand into during firing of the firearm, thereby reducing the noise output of a muzzle blast.
However, as the '944 patent indicates, in a K-baffle ‘The interior chamber and exterior chamber is typically fluidly connected by a flow aperture cut into the forward bell portion.’, such as is not the case in the subject invention. In a typical K-baffle system the flow apertures lead into side chambers which dead-end. In a rapid fire environment, this dead end would saturate with pressure and not blow down properly, leading to increased blowback, which can blow back towards the operator and could stress and potentially damage or disrupt the operating system.